1. Field of the Invention
The present invention relates to a production process of a color filter suitable for use in color liquid crystal displays used in color televisions, personal computers and the like. In particular, the present invention relates to a production process of a color filter for liquid crystals making good use of an ink-jet recording technique, and a color filter for liquid crystals produced in accordance with this production process.
2. Related Background Art
With the spread of personal computers, particularly, portable personal computers in recent years, the demand for liquid crystal displays, particularly, color liquid crystal displays tends to increase. It is however necessary to reduce the cost of the color liquid crystal displays for further disseminating. There is an increasing demand for reduction in the cost of color filters.
Various methods such as those described below have heretofore been attempted for meeting the demand for reduction in the cost of color filters while satisfying the properties required of the color filters. However, no method satisfying all the required properties is yet established under the circumstances.
The first method most often used as a production process of color filters is a dyeing process. In the dyeing process, a sensitizing agent is added to a water-soluble polymeric material, which is a material for dyeing, to sensitize the polymeric material. The thus-sensitized polymeric material is applied on a glass base. After the coating film thus formed is patterned in the desired form by a photolithograph process, the glass base on which the coating film has been patterned is immersed in a dye bath to obtain a colored pattern. This process is repeatedly performed three times separately with coloring materials of different colors to form a color filter layer composed of three colored patterns of red, green and blue (hereinafter abbreviated as "R", "G" and "B", respectively).
The second method often used is a pigment dispersing process which has been replacing the dyeing process in recent years. In this process, a layer of a photosensitive resin in which a pigment of an R, G or B color has been dispersed is first formed on a base and then subjected to patterning, thereby obtaining a pattern of a single color. This process is repeatedly performed three times with the color of the pigment varied to form a color filter layer composed of three colored patterns of R, G and B.
As the third method, there is an electrodeposition process. In this process, a transparent electrode is first patterned on a base. The base is then immersed in an electrodeposition coating fluid containing a pigment, resin, electrolytic solution and the like to electrically deposit the first color. This process is repeatedly performed three times to form a color filter layer composed of three colored patterns of R, G and B. Finally, the color filter layer is calcined to be finished.
As the fourth method, there is a printing process in which three coatings of R, G and B colors, each comprising a thermosetting resin and a pigment dispersed therein, are separately applied by repeated printing, and the resin to become each colored layer is then thermoset to form a color filter layer composed of three colored patterns.
It is the general practice to form a protective layer on the colored layers formed in each process.
The need for repeating the same process three times to form the colored patterns of R, G and B is common to the above-described four production processes. Consequently, the production process becomes complicated, and the production cost is necessarily increased. There is also the problem that the yield is reduced as the number of processes increases.
In the third process by electrodeposition, besides, formable patterns are limited. This process hence involves a problem that it cannot be applied to a TFT color liquid crystal display in the existing technique. The fourth process involves the drawback that resolution and smoothness are poor, and is hence accompanied by the problem that high-definition patterns fine in pitch cannot be formed.
In order to solve these drawbacks, a color filter has been produced by using an ink-jet system to apply inks of R, G and B colors to a glass base having a black matrix. Such processes are described in, for example, Japanese Patent Application Laid-Open Nos. 59-75205, 63-235901, 1-217302 and 4-123005. However, even if this method is used, the production cost of the color filter remains great because the black matrix used is formed from a metal. In addition, the pattern of the black matrix also cannot be changed easily.